Pressure sensors are widely employed in many environments in order to monitor pressure. For instance, pressure sensors may operate in harsh environments such as monitoring pressure in internal combustion engines or aircraft engines, as well as in other environments subjected to high pressures or high temperatures. In a typical pressure sensor, a pressure sensing element may be packaged in a round, glass-metal seal header. This header may be welded onto a screw housing. The screw housing may be mounted to a mating surface such as associated with a port of an engine, forming a seal between the screw housing and the mating surface. Since the seal is formed by the screw housing and the mating surface, any stress caused by the seal may not be transferred to the header. This configuration may work well for many applications but may not work well for applications requiring a seal associated with the front of a sensor. The use of a sensor having a front seal is common in combustion measurements requiring a reduced volume. For a typical sensor having a front seal, the seal may be formed, for instance, directly between the header surface and the surface of the engine or on an adaptor welded to the housing, which may be in close proximity to the header. However, the front seal may place undue stress on the header, which may cause this stress to be transferred to the sensing element.
FIG. 1 shows a prior art sensor 100 having a front seal. A glass seal header 101 is coupled to a sensing element 102. For many applications, this may be done using a piezoresistive leadless sensor. These sensors are made of silicon and have been widely employed. In one example of such sensor, reference is made to U.S. Pat. No. 5,955,771, entitled “SENSORS FOR USE IN HIGH-VIBRATIONAL APPLICATIONS AND METHODS FOR FABRICATING THE SAME” issued on Sep. 21, 1999 to A. D. Kurtz, et al. and assigned to Kulite Semiconductor Products Inc, the assignee herein. In another example, reference is made to U.S. Pat. No. 5,973,590, entitled “ULTRA THIN SURFACE MOUNT WAFER SENSOR STRUCTURES AND METHODS FOR FABRICATING THE SAME” issued on Oct. 26, 1999 to A. D. Kurtz, et al. and assigned to Kulite Semiconductor Products Inc, the assignee herein. Each of these patents is incorporated herein in their entirety. This configuration allows use of the front seal sensor 100 in high temperature, high vibration environments. The glass seal header 101 is welded to a screw housing 103, which allows the front seal sensor 100 to be threaded into a port of, for instance, an engine. The glass seal header 101 encloses the sensing element 102. Further, a first adaptor 104 is welded or press fit to the screw housing 103. A second adapter 105 is welded to the first adaptor 104. The second adaptor 105 has a front surface 106, which allows for sealing the front seal sensor 100 against a mating surface during installation. Since this is a metal-to-metal seal, a large amount of stress is generated in forming the seal. This stress is transferred to the sensing element 102, which may result in reduced accuracy of measurements made by the sensing element 102. Accordingly, there is a need for techniques to allow for reducing an amount of stress transferred to a sensing element of a sensor having a front seal. Further, there is a need for techniques to improve pressure sensors having a Helmholtz resonator. In addition, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and claims, taken in conjunction with the accompanying figures and the foregoing technical field and background.